<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title>原型链</title>
</head>
<body>
<script>
    function Humans(){
        this.foot=2;
    }
    Humans.prototype.getFoot=function(){
       return this.foot;
    }
    function Man(){
        this.head=1;
    }
    Man.prototype=new Humans();
    Man.prototype.getHead=function(){
        return this.head;
    }
    var man1=new Man();
    alert(man1.getFoot());
    alert(man1.getHead());
    alert(man1 instanceof Object);
    alert(man1 instanceof Humans);
    alert(man1 instanceof Man);
</script>
</body>
</html>